Conductor



April 6, 937. A, H; MADE 2,075,906

CONDUCTOR Filed April 6, 1952 I N V EN TOR.

96M H. mw@

f in insulation;

patented Apr. 6, 1937 UNITED STAT l' PATE 7 Claims.

This invention relates to improvement in conductors for use with electrical apparatus and more particularly to those conductors employed in electric motors and electromagnets, transformers,V 5 generators, or the like.

An important object of this invention is to pro vide a conductor which will permit expansion or contraction of the same under varying temperature changes while in use.

Another important object of this invention is to provide a conductor which will permit the same to be used in coils and embedded in an insulating material whereby the latter is unaffected by varying temperature changes.

Another important object of this invention is to provide a conductor for use with electrical apn paratus and which is adapted to be insulated with a vitreous enamel or inorganiccement whereby the same can be used at a high temperature with-l 20 out affecting the insulation due to the expansion 25 than that of the conductor element.

A still further object of this invention is to provide a. conductor of the above character which is of simple' construction, easily manufactured and which may be produced at a reasonable cost.

These and other objects and advantages will be apparent throughout the course of the follow ing description and drawing; in which Fig. i is a cross sectional view oi a conductor constructed of a tube or tubular sheath embedded Fig. 2 is a cross sectionai view of a tubnier c..

and, having conductor ther contact with st tributar conductor;

ss sectional view' ci a .closed in Fig. 2 with the t split nclosed in `ar conductor of overlapped to Fig. e. the

closed in Fig. l Icetteeter ni` cross secti im Fig. 8 is a modification of the construction shown in Fig. '1 in which the tubular casing is split longitudinally at diametrically opposite points whereby to permit additional expansion of the conductor sheath.

Referring in detail to the drawing, l designates insulation which is preferably formed of a vitreous enamel or inorganic cement as distinguished from an insulation which contains organic matters such as cotton or varnish. The dominant characteristic of this insulation is such that it has a thermal expansion less than that oi the conductor with which the same is to be used.

A hollow or sheath like conductor element 2 is embedded in the insulation I and is adapted to receive a solid conductor element 3. The conductor element 3 as shown in Fig. 2 is solid in cross section and is loosely disposed within the conductor sheath 2 so as to provide a space ben tween the circumference of the conductor 3 and the conductor sheath 2. That is, the solid conductor is poked through the tubeA of sheath. There is at least line contact between these elements,'or frequent point contact between the sheath and the solid conductor.

The modications as shown in Figs. 3 and 4 comprise an insulation 4, a conductor element i and a conducting sheath having a longitudinal.

slit or opening as at l.

In the modification shown in Fig. 5 a conductor sheath is provided with a longitudinal slit simim lar to that shown :in Figs. t and 4 and the opposed free edges ci the sheath il and i@ adjacent the .slit are overiappec'. one free edge being embedded i the insuiation as at ii and the other free edge s to permit saine to nieve 'wing reiation in either direcu ception that the sheath li is longitudinally slit at diametrically opposite points as at il so as to permit the sections oi the sheath to move relative to the conductor under varying temperature changes.

Under certain conditions the solid conductor may be eliminated, and the current carried by the sheath alone.

n proceeding in accordance with the present l0 invention, a length of soit annealed copper having a cross section similar to Fig. 2 is covered with asbestos paper and then wound into the form of a coil. This coil is then impregnated with a sodium silicate solution, following which it is slowly dried and baked, the sodium silicate serving to cement the turns oi the coil together. 1n the form shown in Fig. 7 a helical coil of soit annealed copper is formed with mica strips separating the turns. When the first layer is completed it is enameled with a readily fusible vitreous enamel. Successive layers are then wound over the rst layer and each successive layer is then enameled until the coil is completed.

A; coil may be constructed of aluminum having a cross section similar to diagram 2 being heavily coated on the outside of the tubular portion of the conductor with an oxide or phosphate. The space between the coils is then impregnated with a readily fusible vitreous enamel by vacuum and/or pressure.

A still further manner of practicing the invention may consist of placing a plurality of lengths of copper oi square cross section within thin walled tubes of rectangular cross section formed of a nickel iron alloy externally plated with copper. The tubes are then enameled on the exterior surface and placed in the position which they will occupy in the finished coil. This formation is then heated to a temperature at which the enamel flows together to form a. continuous binding. The ends oi the pieces are then connected in any suitable way to form a continuous conductor. This method is particularly suitable where a large portion of the coil is composed oi parallel straight lengths having a crosssectionalarea of 1A; X V8 inches or more. The

space between the copper rod or conductor and liormed of conducting material is covered with inorganic insulation having coefficient of eztp nsion not greater than the sheath. A conduc element of a small diameter is then cced within said sheath so as to provide a space uni erentially about the conductor between the latter and the sheath, wherei Cil insulation under varying temperarnu'e chc ges prevent the cracking or splitting ie insulation. This arrangement further its moveent of the conducting ement in all directions hin the protecting orconclucting sheath with.u out manning or damaging the insulation..

is to be understood that 22 operation, a hollow sheath which may amples of coil construction are merely a few of the ways by which the invention may be practiced and is not to be construed in any way as limiting the uses to which the invention may be placed.

Additional legends on the drawing are merely by way of illustration and they are not to be construed as limiting the disclosure in any way.

Having thus described my invention, what I claim, is:

l. An electrical conductor comprising a solid conducting element, and insulating material surrounding and spaced from said element, and a relatively thin conducting sheath held to said insulating material and loosely surrounding said elementand normally having line contact therewith, said sheath being constructed of material having substantially the same coefficient of expansion as that of said insulating material, said solid conducting element -being constructed of material having any reasonable coeiiicient of expansion whatever.

2. An electrical ,conductor comprising a solid conducting element, and insulating material which will withstand a temperature of degrees centigrade surrounding and spaced from said element, and a relatively thin conducting sheath held to said insulating material and loosely surrounding said element and normally having line contact therewith, said sheath being constructed of material having substantially the same coefcient of expansion as that of said insulating material, said solid conducting element being constructed of material having any reasonable coefficient of expansion Whatever.

3. An electrical conductor comprising a solid conducting element, and insulating material consisting of a vitreous enamel surrounding and spaced from said element, and a relatively thin conducting sheath held to said insulating material and loosely surrounding said element and normally having line contact therewith, said sheath being constructed of material having substantially the same coeihcient oi expansion as that oi said insulating material, said solid conducting element being constructed of material having any reasonable coemcient of expansion whatever.

Lin electrical conductor comprising a solid .conducting element, and insulating material con sisting of an inorganic cement surrounding and spaced from said element, and a relatively thin conducting sheath held to said insulating ma terial and loosely surrounding said element and normally having line contact therewith, said sheath being constructed of material having sub-- ste ally the same coencient ci expansion as the iorin of coil element, and in ng a solid conducting and spaced from sheath held to said insulating material and loosesiLrsun ing said element normally hav" e" line contact therewith, said sheath being ci s ucted of material having substantially construct-ed oi material having any rca sonable coefdcient of expansion whatever'.

6. n n electrical conductor comprising a soltl ernal conducting portion, a thin conducting ion and spaced from said ina u, @maxim www@ said material having a oontaol;

s, thermal Glosse to that; of salcl tkm olmductw no and; thermal stability so high that my amours when exposed to le, tompm'atwm l5@ dogmes @antimafia Y". An @Mammal conductor comprimi ozemail conducting portion, a thm parta-m swrounding and spaced' im termal pmlom 9,1m; normally havmfj liesfevdg to permit normal Mmmm@ ai solid imemal portion, :saldi @www tion heil? lusulaieel with am nlsl@ im @xafor surtaxe@ sael material Moving a@ marmol expansion so close to llama of said thm oonduolzmg portion and thexml stabili@ mgm tlm: no injury oocwfs when exposed to Veronel @Walsum of l5@ degrees cengmd, hm mmuctmg; portion and said insulazlzg mmtex'al moving approximalely the sam@ oodoem; of Slermal expansion, said solid mlemofl potom being: oomtmotecl of material having im rea,- somlol@ oololen; of expansion Wlmtevelu 

